1. Field of the Invention
The invention relates to a printer for feeding a printed sheet (paper), which has been printed between a thermal head and a platen, by paired feed rollers provided downstream the thermal head in the feeding direction and, more specifically, to a printer suitable for using a printable sheet composed of a double film.
2. Description of the Related Art
As a printing portion of a conventional printer for performing printing on a printable sheet by a thermal head and a platen, for example, there is one shown in FIG. 8. The printing portion of this printer performs printing by a thermal head 61 while a platen 62 is rotated by a driving power source in the direction of the arrow denoted at A with a printable sheet 63 and a thermal transfer ribbon 64 sandwiched between the thermal head 61 and the platen 62.
However, in the case of a printer structured such that the platen to which the thermal head is pressed to contact through the printable sheet and the thermal transfer ribbon (only the printable sheet when it is thermal paper), as described above, is rotated by turning effort applied from the driving power source, there often occurs a problem depending on the kind of printable sheet in use.
Such a problem occurs, for example, when a printable sheet 68 is used which is in a form of double film, made by folding a film into two of a film 68a and a film 68b, folded at one edge side with the other edge side open with respect to the feeding direction of the arrow denoted at D as shown in FIG. 9. In other words, when printing is performed on the printable sheet 68, the film 68b contacting the platen 62 is fed by the feeding force of the platen 62, but the film 68a on the thermal head 61 side is hard to be fed due to occurrence of slippage with respect to the film 68b as shown in FIG. 10.
Thus, in this case, wrinkles occur on the printable sheet 68 as shown in FIG. 10 and it can not be fed in a proper manner.
The present invention is made in viewpoint of the above-described problem, and its object is to make it possible to perform printing on a printable sheet, even if a printable sheet composed of a double film is used, and to surely feed it.
In order to attain the above object, in a printer for feeding a printed sheet which has been printed between a thermal head and a platen by paired feed rollers provided downstream the thermal head in a feeding direction, the platen is rotatably provided free from being rotated by a driving power source, and one roller of the paired feed rollers located on the thermal head side with respect to the printed sheet is a driving roller which is rotated by the power source, and the other roller located on the platen side is a driven roller which is not rotated by the driving power source.
In the above-described printer, it is preferable to provide a moving member on which the thermal head and the driving roller, or the platen and the driven roller are mounted, the moving member being held on a fixing portion to be movable in a direction in which the thermal head and the platen, and the driving roller and the driven roller, respectively, approach to, or separate from, each other, so that when the moving member is moved in the direction of separation, portions between the thermal head and the platen and between the driving roller and the driven roller are both exposed to an outside of the printer.
Further, it is preferable that a portion of the driving roller contacting the printed sheet is formed of nonadhesive rubber.
Further, it is suitable to provide, similarly to the above-described printer, a moving member on which the thermal head and the driving roller, or the platen and the driven roller are mounted, the moving member being held on a fixing portion to be movable in a direction in which the thermal head and the platen, the driving roller and the driven roller, respectively, approach to, or separate from, each other; paired pressing rollers continuously pressing against each other provided downstream of the driving roller and the driven roller in a feeding direction of the printed sheet; and driving means for independently rotating the pressing roller.
The above and other objects, features and advantages of the invention will be apparent from the following detailed description which is to be read in conjunction with the accompanying drawings.